Macroinvertebrates as monitors of river health in the tropics

Pearson, Richard, and Connolly, Niall (1998) Macroinvertebrates as monitors of river health in the tropics. Report. James Cook University, Townsville, QLD, Australia.

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Aquatic invertebrates are used throughout the world in monitoring water quality conditions. Water quality assessment is often based on "grab" samples that may only represent the conditions for only a short period. Continuous monitoring of water quality parameters over an extended period is usually unavailable due to prohibitive costs. Invertebrates have been used as an indicator of water quality representing an integration of the conditions over a longer time scale. However, very little evidence is available that confidently identifies the tolerances of specific invertebrate taxa or assemblages to environmental conditions. This greatly reduces the sensitivity of· invertebrates as indicators of changing conditions. Many surveys using invertebrates as indicators can only confirm changes that can be detected using other methods, such as measuring water quality parameters, but have limited predictive value on their own. Without information on the specific tolerances of invertebrate fauna that will allow accurate predictions of water quality conditions, the sensitivity of invertebrates as indicators is weakened. This problem is exacerbated by less than optimum replication, independence, grain and extent of sampling, and a host of confounding effects.

It is clear from the large variety of methods available that a consensus on the use of invertebrates as monitors has not been reached. In Australia the Monitoring River Health Initiative (MRHI) was established within the Land and Water Resources Research and Development Corporation (LWRRDC) to develop a monitoring program based on invertebrates that applied across the continent, with state agencies and the Commonwealth contributing to development of a rigorous and generally adopted methodology. One of the main precepts of this approach is that stream invertebrate species respond differentially to different conditions of habitat, water quality and disturbance and so can give an integrated indication of the recent history of a particular site. There are many case studies that support this precept, including publications on Australian systems. However, some of the reasoning based on empirical evidence can be regarded as circular. There is little experimental evidence at the community level to back up monitoring schemes, by calibrating responses of invertebrate populations and communities to different levels of contamination or disturbance.

As part of the MRHI, this deficiency was recognised and appropriate research was commissioned to address it. This project specifically focussed on tropical streams, which differ substantially from streams elsewhere in the continent in their variability, high temperatures and high fauna! diversity. The approach required was to use mesocosms to control environmental conditions and so arrive at quantitative relationships between contaminants and the invertebrate fauna. This project developed several experimental systems for this purpose. Additionally, in conjunction with a parallel project (JCU8 - Stream ecosystems as monitors of tropical forest catchments), it examined an extensive database of empirical information on invertebrate occurrence and water quality. This it set in the context of perceived problems in water quality, which were ascertained through a community survey.

Item ID: 36645
Item Type: Report (Report)
Additional Information:

ACTFR Report No. 98/20

Projects and Grants: LWRRDC Project: JCUll
Date Deposited: 14 Dec 2016 01:13
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 100%
SEO Codes: 96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960604 Environmental Management Systems @ 100%
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